A liquid crystal display having a touch detection device what is called a touch panel (hereinafter, referred to as a touch sensor) has been known. The liquid crystal display is configured such that a liquid crystal panel is overlaid with a touch sensor, and various types of buttons are displayed as images on the liquid crystal display screen to thereby allow information to be input using such buttons instead of conventional buttons. By applying this technology to a small-sized mobile device, a display and placement of buttons can be made in common, which provides significant advantages such as enlargement of a screen, reduction in the space of an operation unit, and reduction in the number of components.
However, the structure in which the liquid crystal panel is overlaid with the touch sensor causes a problem that the entire liquid crystal module becomes thick. As such, in order to make it thinner, for example, a liquid crystal display having a touch sensor has been proposed in which a conductive film for the touch sensor is provided between a monitoring-side substrate of the liquid crystal display element and a polarizer for observation disposed on the outside thereof, and a capacitance type touch sensor, in which the outer surface of the polarizer is used as a touching face, is formed between the conductive film for the touch sensor and the outer surface of the polarizer (for example, see Patent Document 1).
FIG. 1 illustrates a control block diagram regarding display control processing of a personal computer using a liquid crystal display having a touch sensor.
The personal computer includes an LCD module 10, and as a processing unit of the host side for controlling it, a host processing unit 14. The LCD module 10 includes a touch panel display 11, and driver ICs 12 and 13.
The touch panel display 11 is configured of a touch panel 21 and an LCD panel 22, the driver IC 12 is a control IC (Integrated Circuit) for the touch panel 21, and the driver IC 13 is a control IC for the LCD panel 22.
The driver IC 12 includes a touch panel driver 31, a detection circuit 32, and a coordinate conversion circuit 33.
The touch panel driver 31 scan-drives belt-shaped conductive film lines arrayed in multiple numbers in an X-axis direction and a Y-axis direction, respectively, on the touch panel 21. The detection circuit 32 detects an analog sensor signal representing a capacitance value corresponding to presence/absence of a touch (contact) by a user at a given position on the touch panel 21, according to the scan-driving of the touch panel driver 31, and AD-converts it to a digital signal. The coordinate conversion circuit 33 converts the digital sensor signal representing the touch detection position detected by the detection circuit 32 into a two-dimensional coordinate position expressed by the X coordinate position and the Y coordinate position of the touch panel 21, and outputs it to the host processing unit 14 as raw coordinate information.
The driver IC 13 includes an LCD driver 41, a memory 42, and a timing controller 43.
To the driver IC 13, display data of display information A, based on the result of operation such as calibration and filtering performed on the raw coordinate positions indicating the touch position output from the driver IC 12, is supplied from the host processing unit 14.
The LCD driver 41 drives, in a predetermined sequence, respective pixels of the LCD panel 22 arrayed in multiple numbers two-dimensionally based on the display data stored in the memory 42, in order to allow the display information A supplied from the host processing unit 14 to be displayed. The memory 42 stores display data of the display information A supplied from the host processing unit 14. The timing controller 43 obtains the display data of the display information A supplied from the host processing unit 14 and stores it in the memory 42.
The host processing unit 14 includes a CPU (Central Processing Unit) 51, a memory (RAM: Random Access Memory) 52, a graphics controller 53, and an image memory (VRAM) 54.
The CPU 51 is a processor which controls the whole personal computer, and executes device drivers of the respective devices provided to the personal computer, the operation system (OS), application programs, and the like. The memory 52 stores data necessary for performing given processing by the CPU 51, namely, an execution program and the like, for example.
Further, when the CPU 51 obtains raw coordinate position indicating the touched position by the user from the driver IC 12 of the LCD module 10 as raw coordinate information, the CPU 51 calculates the centroid of the raw coordinate position, performs equalization, and the like, to thereby accurately calibrate the touched position by the user, and calculates the touched position after the calibration (calibration coordinate position).
The graphics controller 53 is a processor for displaying an image on the LCD panel 22, and outputs display data of an image to be displayed on the LCD panel 22 to the driver IC 13 of the LCD panel 22, while storing it in an image memory 54 as appropriate. For example, the graphics controller 53 outputs, to the driver IC 13 of the LCD panel 22, display data of the display information A as a display image responding to the touched position, based on the calibration coordinate position of the user.